This application is related to the following U.S. patent applications:
U.S. patent application Ser. No. 09/884,615, filed Jun. 19, 2001 and titled, “Seat Belt Tension Sensor With Overload Protection”.
U.S. patent application Ser. No. 10/202,727, filed Jul. 25, 2002 and titled, “Hall Effect Seat Belt Tension Sensor”.
U.S. patent application Ser. No. 10/185,242, filed Jun. 28, 2002 and titled, “Seat Belt Tension Sensor”.
U.S. patent application Ser. No. 09/441,350, filed Nov. 15, 1999 and titled, “Automobile Seat Having Seat Supporting Brackets with a Stepped Weight Sensor”.
U.S. patent application Ser. No. 09/374,874, filed Aug. 16, 1999 and titled, “Automobile Seat Weight Sensor”.
U.S. patent application Ser. No. 09/374,870, filed Aug. 16, 1999 and titled, “Vehicle Occupant Position Detector and Airbag Control System”.
U.S. patent application Ser. No. 09/422,382, filed Oct. 21, 1999 and titled, “Vehicle Seat Weight Sensor”.
U.S. Pat. No. 6,209,915, issued Apr. 3, 2001 and titled, “Seat Belt Tension Sensor”.
U.S. Pat. No. 6,450,534, issued Sep. 17, 2002 and titled, “Seat Belt Tension Sensor”.
The foregoing patents have the same assignee as the instant application and are herein incorporated by reference in their entirety for related and supportive teachings.
1. Field of the Invention
This invention relates to an automobile sensor for detecting the magnitude of a tensile force in a seat belt used in a car seat, and in particular to a sensor that can detect the magnitude of tension in a seat belt and provide an electrical signal that is representative of the magnitude of tensile force.
2. Description of the Related Art
Air bags have been heralded for their ability to reduce injuries and save lives. However, since their incorporation into automobiles, a problem has existed with people of smaller size and small children. Air bags are designed to cushion the impact of occupants and thus reduce the injuries suffered. However, the force needed to properly cushion the occupant varies based on the size and position of the person.
For example, a larger person requires the bag to inflate faster and thus with more force. A smaller person may be injured by a bag inflating at this higher inflation force. A smaller person is more likely to be sitting close to the dashboard and would therefore stand a higher chance of being injured by the impact of the inflating bag, as opposed to the passenger hitting the fully inflated bag to absorb the impact of the accident. An average-sized person can also be injured by an airbag inflation if they are leaning forward, as for example, if they are adjusting the radio.
Because of the concern over injury to passengers in these situations, the National Highway Transportation Safety Administration (or NHTSA), an administrative agency of the United States, is instituting rules requiring the air bag deployment system to identify the passenger size and position and inflate the air bag accordingly.
One way to accomplish this task is to use a seat belt tension sensor in conjunction with an occupant weight sensor. The weight sensor can provide an indication of the force placed by an occupant on the seat. However, if the seat belt is unduly tightened, it can place an additional downward force on the passenger, creating an erroneous weight reading. Similarly, it is common for infant car seats to be secured tightly to the seat. In this circumstance, it is critical for the system to recognize that the passenger does not warrant inflation of the air bag. By sensing the tension on the seat belt in addition to the weight reading from the seat, the actual weight of the occupant can be determined. This allows for the system to safely deploy the air bag.